Until now the production of the cover box for a telescopic cover used to cover and protect a machine tool guideway has been very complicated. First of all outlines have to be made (so-called tracing) on the blank which is to form the top wall and the side walls in order to mark the stamping and bending lines. After the stamping operation (production of cut-outs) comes the longitudinal bending of the angles which later serve for connection to the rear wall. Then the flanks are bent. In order for the basic body which has been prepared in this way to be connected to the rear wall, both parts must then be clamped true to size before the welding or riveting can be carried out.